Watch Live Sunday as Orbital Sciences’ Spacecraft Berths With the ISS

UPDATE: 9/22/13 4:15 a.m. EDT – Cygnus rendezvous with the ISS has been waived off for 48 hours due to a “data link issue between the spacecraft and the station” according to Orbital Sciences.

Orbital Sciences’ Cygnus spacecraft is on its way to the International Space Station. After a flawless launch from the Wallops Island Flight Facility on the Virginia Coast on Tuesday, the spacecraft has performed two of the demonstrations NASA is requiring. Cygnus will continue to close in on the ISS, performing the final eight maneuvers on Sunday before being berthed at the station.

After the Antares rocket boosted Cygnus into a low Earth orbit, the Orbital Sciences team performed three burns of the spacecraft’s engines to raise its orbit and begin the approach to the ISS. The third “delta V” burn occurred yesterday afternoon and lasted 189 seconds, for a 20.7 meter per second change in velocity. The fourth and final scheduled delta V burn is scheduled for this afternoon.

With the orbital burns complete, Cygnus will catch up with and make its approach to the station Saturday and into early Sunday. A little after 5:00 a.m. EDT Sunday, the spacecraft will reach a point 250 meters below the station. Orbital Sciences will perform the final eight demonstration maneuvers, including an aborted approach, before taking the final few steps to the station. The spacecraft will stop 10 meters from the station, where it will be placed in “free drift” mode, meaning the onboard navigation is no longer controlling its location.

Once in free drift, astronaut Karen Nyberg will reach out with the station’s robotic arm and slowly bring the Cygnus the final few meters to be berthed to the ISS a little after 9:00 a.m. EDT.

Image: Analytical Graphics Inc.

The live NASA feed is posted above for those who want to wake up early Sunday to watch the event live. But you can also watch the Cygnus flight in orbit and approach to the station right now thanks to an amazing simulation from Analytical Graphics Incorporated. The sim shows the Cygnus in its current position, as well as its entire flight to the ISS. The sim is based on the predicted data from Orbital Sciences and accurately shows Cygnus’ flight.

“It is based on our flight control center and what their predictions for the coming day are, and they will update it on a regular basis,” says Carlos Niederstrasser, a mission engineer at Orbital.

The AGI sim uses the same core engine that is used by Orbital Sciences for its own simulations, as well as mission planning.

“That’s what we use for all of our orbit determinations, it’s what we use for the trajectory planning, for planning all of the delta V engine maneuvers whenever we fire up the engines on Cygnus,” Niederstrasser says. “It’s exactly the same core engine, same physics, same mathematics that they utilize.”

The data for both the sim and the software used by Orbital is updated several times a day with data from the spacecraft. After each delta V burn, and as the final approach is made, the team at mission control will use their much fancier version of the sim to recalculate and refine the spacecraft’s orbit and approach.

Once berthed to the station, Cygnus is expected to stay at the ISS for 30 days. After that it will be released and after a short flight, its orbit will decay and the spacecraft will burn up upon reaching the upper reaches of the atmosphere.